Field effect transistor
AssigneeNichia Corporation
InventorsMitsuo Hayamura, Shiro Akamatsu
Life of this patent
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Abstract
A FET includes a nitride semiconductor in which leak current is reduced and breakdown voltage is improved. The FET is formed from a substrate, a buffer layer made of a nitride semiconductor, a first semiconductor layer made of a nitride semiconductor, and a second semiconductor layer made of a nitride semiconductor, wherein at least the buffer layer and the first semiconductor layer include a p-type dopant. The concentration of the p-type dopant is higher in the buffer layer than that in the first semiconductor layer, and the concentration of the p-type dopant is higher in the first semiconductor layer than that in the second semiconductor layer.
Claims17
A field-effect transistor comprising:
- a substrate;
- a buffer layer comprising a nitride semiconductor over the substrate;
- a first semiconductor layer comprising a nitride semiconductor over the buffer layer;
- and
- a second semiconductor layer comprising a nitride semiconductor over the first semiconductor layer,
- wherein at least said buffer layer and said first semiconductor layer contains a p-type dopant,
- a concentration of the p-type dopant in said buffer layer is higher than a concentration of the p-type dopant in said first semiconductor layer, and
- a concentration of the p-type dopant in said first semiconductor layer is higher than a concentration of the p-type dopant in said second semiconductor layer.
A method for producing a field-effect transistor comprising steps of:
- providing a substrate;
- forming a buffer layer comprising a nitride semiconductor over the substrate;
- forming a first semiconductor layer comprising a nitride semiconductor over the buffer layer;
- and
- forming a second semiconductor layer comprising a nitride semiconductor over first semiconductor layer,
- wherein at least said buffer layer and said first semiconductor layer contains a p-type dopant,
- a concentration of the p-type dopant in said buffer layer is higher than a concentration of the p-type dopant in said first semiconductor layer, and
- a concentration of the p-type dopant in said first semiconductor layer is higher than a concentration of the p-type dopant in said second semiconductor layer.
A field-effect transistor comprising:
- a substrate;
- an underlayer over the substrate, the underlayer comprising at least a first semiconductor layer and a partial region of a second semiconductor layer;
- and
- an active region comprising a nitride semiconductor over the underlayer,
- wherein the first semiconductor layer comprises a nitride semiconductor and the second semiconductor layer comprises a nitride semiconductor, and said first semiconductor layer contains a p-type dopant, a concentration of the p-type dopant in the first semiconductor layer is higher than a concentration of p-type dopant in the second semiconductor layer, and the underlayer is formed as a semi-insulating, i-type layer.
Dependencies are inferred from the claim text.